WO2012043453A1

WO2012043453A1 - Epoxy resin composition, prepreg and fiber-reinforced compound material

Info

Publication number: WO2012043453A1
Application number: PCT/JP2011/071842
Authority: WO
Inventors: 林真実; 藤原隆行; 三角潤; 吉岡健一
Original assignee: 東レ株式会社
Priority date: 2010-09-28
Filing date: 2011-09-26
Publication date: 2012-04-05
Also published as: KR20130108351A; EP2623533A1; RU2013119741A; TWI513755B; CN103140536A; KR101569595B1; US20130217805A1; EP2623533A4; US9738782B2; CA2811881A1; TW201224048A; EP2623533B1; CN103140536B

Abstract

The epoxy resin composition is an epoxy resin composition containing epoxy resin [A1], epoxy resin [B1], epoxy resin [C1] and curing agent [D], wherein [A1] is a bisphenol epoxy resin with softening point of 90°C or more, [B1] is a tri-functional or higher amine epoxy resin, and [C1] is a bisphenol F epoxy resin with number average molecular weight of 450 or less, and the epoxy resins [A1]-[C1] satisfy the blending ratio of 20-50 parts by mass of [A1], 30-50 parts by mass of [B1] and 10-40 parts by mass of [C1] with respect to 100 parts by mass of the total epoxy resin components. The invention provides an epoxy resin composition of low viscosity and excellent impregnation between reinforcing fibers that forms cured resin products having both excellent elastic modulus and toughness, as well as a prepreg and a fiber-reinforced compound material that use the epoxy resin composition.

Description

Epoxy resin composition, prepreg and fiber reinforced composite material

The present invention relates to an epoxy resin composition preferably used as a matrix resin of a fiber reinforced composite material suitable for sports applications and general industrial applications, and a prepreg and a fiber reinforced composite material using the epoxy resin composition as a matrix resin.

Fiber reinforced composite materials using carbon fibers, aramid fibers, etc. as reinforcing fibers make use of their high specific strength and specific modulus to make structural materials such as aircraft and automobiles, sports applications such as tennis rackets, golf shafts and fishing rods Widely used in general industrial applications. As a method for producing these fiber reinforced composite materials, a method is often used in which a prepreg, which is a sheet-like intermediate material in which reinforcing fibers are impregnated with a matrix resin, is laminated and then cured. The method using a prepreg has an advantage that a high-performance fiber-reinforced composite material can be easily obtained because the orientation of the reinforcing fibers can be strictly controlled and the degree of freedom in designing the laminated structure is high. As the matrix resin used for the prepreg, a thermosetting resin is mainly used from the viewpoint of heat resistance and productivity, and an epoxy resin is preferably used from the viewpoint of mechanical properties such as adhesion to reinforcing fibers.

In recent years, in addition to the movement to reduce weight by replacing conventional materials such as metals with fiber reinforced composite materials, there has been an active movement for further weight reduction of the fiber reinforced composite materials themselves in various applications. As a method for achieving weight reduction, there is a method of using a reinforcing fiber having a higher elastic modulus and reducing the weight while maintaining the rigidity of the fiber-reinforced composite material. However, when the elastic modulus of the reinforcing fiber is increased, strength characteristics such as fiber direction compressive strength tend to be lowered. In order to improve strength characteristics such as fiber direction compressive strength, it is effective to improve the elastic modulus of the epoxy resin used as the matrix resin.

Measures for improving the elastic modulus of the epoxy resin include addition of inorganic fillers such as carbon nanotubes and blending of an amine type epoxy resin having a high elastic modulus.

For example, in Patent Document 1, by adding an amine-type epoxy resin having a high elastic modulus, the elastic modulus of the epoxy resin is improved, and in a fiber-reinforced composite material in which this is applied as a matrix resin, there is a correlation with the fiber direction compressive strength. A significant improvement in strong fiber direction bending strength has been observed. However, in this method, since the toughness of the epoxy resin is lowered, the impact resistance is lowered.

In order to improve the impact resistance of the fiber reinforced composite material, it is necessary to improve the elongation of the reinforcing fiber constituting the fiber reinforced composite material and the plastic deformation ability and toughness of the epoxy resin. Of these, it is particularly important to improve the toughness of the epoxy resin.

Conventionally, as a method for improving the toughness of an epoxy resin, a method of blending a rubber component having excellent toughness or a thermoplastic resin has been tried. However, since the elastic modulus and glass transition temperature of rubber are significantly lower than those of epoxy resin, when blended with epoxy resin, the elastic modulus and glass transition temperature of epoxy resin are reduced, and the balance between toughness and elastic modulus is found. Is difficult to take. Further, as a method of blending the thermoplastic resin, for example, by blending a block copolymer such as a copolymer composed of styrene-butadiene-methyl methacrylate or a block copolymer composed of butadiene-methyl methacrylate, Methods for greatly improving the toughness of epoxy resins have been proposed (Patent Documents 2 and 3). However, these methods have problems such as reduced heat resistance, deteriorated processability due to thickening, and reduced quality such as void generation. Also, this method has an insufficient elastic modulus.

As a method for improving the balance between elastic modulus and toughness, a method is disclosed in which a diglycidyl ether type epoxy resin having a specific number average molecular weight and an epoxy resin having a different SP value in a specific range are combined ( Patent Document 4). However, even this method is not only insufficient in balance between elastic modulus and toughness, but also tends to increase in viscosity.

JP-A-62-1717 International Publication No. 2006/075153 Pamphlet Special Table 2003-535181 International Publication No. 2009/107697 Pamphlet

An object of the present invention is to improve the drawbacks of the prior art, provide a cured resin having both excellent elastic modulus and toughness, and has a low viscosity and excellent impregnation between reinforcing fibers, and Another object is to provide a prepreg and a fiber reinforced composite material using the epoxy resin composition. Here, the cured resin means a cured epoxy resin or epoxy resin composition. The same applies hereinafter.

As a result of intensive studies to solve the above problems, the present inventors have found an epoxy resin composition having the following constitution, and have completed the present invention. That is, this invention consists of the following structures.
An epoxy resin composition comprising an epoxy resin [A1], an epoxy resin [B1], an epoxy resin [C1] and a curing agent [D], wherein [A1] is a bisphenol type epoxy resin having a softening point of 90 ° C. or higher, [ B1] is a tri- or higher functional amine type epoxy resin, and [C1] a bisphenol F type epoxy resin having a number average molecular weight of 450 or less, and the epoxy resins [A1] to [C1] are contained in 100 parts by mass of all epoxy resin components. On the other hand, an epoxy resin composition satisfying a compounding ratio of [A1] 20 to 50 parts by mass, [B1] 30 to 50 parts by mass and [C1] 10 to 40 parts by mass.
(2) Epoxy resin composition containing epoxy resin [A2], epoxy resin [B2], epoxy resin [C2] and curing agent [D] and satisfying the following conditions (1) to (4):
In another aspect of the present invention, the SP value of the cured resin [B2 ′] obtained by reacting and curing the epoxy resin [B2] with the curing agent [D] has epoxy resins [A2] and [C2]. Is larger by 1.2 or more than the SP value of any of the cured resin products [A2 ′] and [C2 ′] obtained by reacting and curing with the curing agent [D];
(2) The softening point of the epoxy resin [A2] is 90 ° C. or higher, and the softening points of the epoxy resins [B2] and [C2] are both 50 ° C. or lower;
(3) Epoxy resin [C2], dicyandiamide having an active hydrogen group of 0.9 equivalent to the epoxy group of epoxy resin [C2], and 2 parts by mass of 3- (3) to 100 parts by mass of epoxy resin [C2] Cured resin obtained by heating an epoxy resin composition comprising 3,4-dichlorophenyl) -1,1-dimethylurea from room temperature to 130 ° C. at a rate of 2.5 ° C./min and reacting at 130 ° C. for 90 minutes. And (4) a cured resin obtained by curing the epoxy resin composition has a phase separation structure including [A2] rich phase and [B2] rich phase. The period of the phase separation structure is 1 nm to 1 μm.
Moreover, this invention contains the prepreg containing said epoxy resin composition and a reinforced fiber.
Moreover, this invention contains the fiber reinforced composite material formed by hardening said prepreg.
Moreover, this invention contains the hardened | cured material of said epoxy resin composition, and the fiber reinforced composite material containing a reinforced fiber.

According to the present invention, a fine phase separation structure of an epoxy resin is formed at the time of curing, a high elastic modulus and high toughness resin cured product is obtained, and the epoxy resin composition has a low viscosity and excellent impregnation between reinforcing fibers. Can provide. Moreover, the fiber reinforced composite material which used the hardened | cured material of the epoxy resin composition of this invention as matrix resin has the outstanding static strength characteristic and impact resistance.

As a result of intensive investigations to achieve the above object, the inventors have found that the epoxy resin composition provides an epoxy resin [A] that gives the resin cured product high toughness, and an epoxy resin that gives the resin cured product a high elastic modulus [ B], an epoxy resin [C] that functions as a compatibilizing agent for epoxy resins [A] and [B], and a curing agent [D], and a resin curing obtained by curing the epoxy resin composition It has been found that a cured product having a high elastic modulus and high toughness can be obtained by forming a fine phase separation structure including an epoxy resin [A] rich phase and an epoxy resin [B] rich phase.

Here, even when the epoxy resins [A] to [C] are in a state of being uniformly compatible with each other before curing, the spinodal decomposition occurs in the curing process, and the epoxy resin [A] rich phase and the epoxy resin [ B] It is preferable to form a phase separation structure with the rich phase. Further, the phase separation structure period is more preferably 1 nm to 5 μm, and a more preferable phase separation structure period is 1 nm to 1 μm. In the curing process of the epoxy resin composition, the epoxy resin [C] functions as a compatibilizing agent for the epoxy resins [A] and [B].

When the structural period is less than 1 nm, the cavitation effect cannot be exhibited, and not only the toughness is insufficient but also the elastic modulus tends to be insufficient. In addition, when the structural period exceeds 5 μm, the structural period is large, so the crack does not progress to the island phase, but only in the sea phase. The toughness may be insufficient. That is, the cured product of the epoxy resin composition contains an epoxy resin [A] rich phase and an epoxy resin [B] rich phase, and has a fine phase separation structure, so that the elastic modulus and toughness of the resin cured product can be improved. It is possible to achieve both.

In the present invention, the phase separation structure means a structure in which two or more phases including an epoxy resin [A] rich phase and an epoxy resin [B] rich phase are separated. Here, the epoxy resin [A] rich phase and the epoxy resin [B] rich phase refer to phases mainly composed of the epoxy resin [A] and the epoxy resin [B], respectively. Moreover, a main component means the component contained by the highest content rate in the said phase here. The phase separation structure may be a phase separation structure of three or more phases further including a phase mainly composed of components other than the epoxy resin [A] and the epoxy resin [B]. On the other hand, the state of being uniformly mixed at the molecular level is called a compatible state.

The phase separation structure of the cured resin product can be observed with a scanning electron microscope or a transmission electron microscope. You may dye | stain with osmium etc. as needed. Dyeing can be performed by a usual method.

In the present invention, the structural period of phase separation is defined as follows. The phase separation structure includes a two-phase continuous structure and a sea-island structure. When the phase separation structure is a biphasic continuous structure, draw three straight lines of a predetermined length on the micrograph, extract the intersection of the straight line and the phase interface, measure the distance between the adjacent intersections, These number average values are used as the structure period. The predetermined length is set as follows based on a micrograph. When the structural period is expected to be on the order of 0.01 μm (0.01 μm or more and less than 0.1 μm), a sample photograph was taken at a magnification of 20,000 times, and a length of 20 mm drawn on the photograph (1 μm on the sample) Is a predetermined length of a straight line. Similarly, when the phase separation structure period is expected to be on the order of 0.1 μm (0.1 μm or more and less than 1 μm), a photograph is taken at a magnification of 2,000 times and a length of 20 mm on the photograph (10 μm on the sample) (Length) is a predetermined length of a straight line. When the phase separation structure period is expected to be on the order of 1 μm (1 μm or more and less than 10 μm), a photograph is taken at a magnification of 200 times, and a length of 20 mm on the photograph (a length of 100 μm on the sample) is defined as a predetermined straight line length. To do. If the measured phase separation structure period is out of the expected order, the measurement is performed again at a magnification corresponding to the corresponding order.

When the phase separation structure is a sea-island structure, three predetermined regions on the micrograph are selected at random, the island phase size in the region is measured, and the number average value of these is the structure period. The size of the island phase refers to the length of the shortest distance line drawn from the phase interface to one phase interface through the island phase. Even when the island phase is an ellipse, an indeterminate shape, or a circle or ellipse of two or more layers, the shortest distance passing through the island phase from the phase interface to one phase interface is defined as the island phase size. The predetermined area is set as follows based on a micrograph. When the phase separation structure period is expected to be on the order of 0.01 μm (0.01 μm or more and less than 0.1 μm), a photograph of the sample was taken at a magnification of 20,000 times, and an area of 4 mm square on the photograph (0 on the sample) .2 μm square area) is defined as a predetermined area. Similarly, when the phase separation structure period is expected to be on the order of 0.1 μm (0.1 μm or more and less than 1 μm), a photograph is taken at a magnification of 2,000 times, and an area of 4 mm square on the photograph (2 μm square on the sample) Is defined as a predetermined area. When the phase separation structure period is expected to be on the order of 1 μm (1 μm or more and less than 10 μm), a photograph is taken at a magnification of 200 times, and an area of 4 mm square on the photograph (an area of 20 μm square on the sample) is defined as a predetermined area. If the measured phase separation structure period is out of the expected order, the measurement is performed again at a magnification corresponding to the corresponding order.

Next, specific embodiments of the present invention will be described. A first aspect of the epoxy resin composition of the present invention is an epoxy resin composition comprising an epoxy resin [A1], an epoxy resin [B1], an epoxy resin [C1], and a curing agent [D], wherein [A1] Is a bisphenol type epoxy resin having a softening point of 90 ° C. or higher, [B1] is a trifunctional or higher amine type epoxy resin, and [C1] is a bisphenol F type epoxy resin having a number average molecular weight of 450 or less, and the epoxy resin [A1 ] To [C1] satisfy the compounding ratio of [A1] 20 to 50 parts by mass, [B1] 30 to 50 parts by mass and [C1] 10 to 40 parts by mass with respect to 100 parts by mass of all epoxy resin components. It is a resin composition.

In this embodiment, the epoxy resin [A1] needs to contain 20 to 50 parts by mass of 100 parts by mass of the total epoxy resin of bisphenol type epoxy resin having a softening point of 90 ° C. or higher. Preferably, 30 to 50 parts by mass of the epoxy resin [A1] is included in 100 parts by mass of the total epoxy resin. When the softening point of the epoxy resin [A1] is less than 90 ° C., the toughness of the cured resin is insufficient. Moreover, when content of epoxy resin [A1] is less than 20 mass parts, the toughness of resin cured material is insufficient. When the content of the epoxy resin [A1] exceeds 50 parts by mass, not only the elastic modulus and heat resistance of the resin cured product are insufficient, but also the viscosity of the epoxy resin composition becomes too high. If the viscosity of the epoxy resin composition becomes too high, the epoxy resin composition cannot be sufficiently impregnated between the reinforcing fibers when the prepreg is produced. For this reason, voids are generated in the obtained fiber reinforced composite material, and the strength of the fiber reinforced composite material is lowered.

The epoxy resin [A1] is selected from bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, bisphenol S type epoxy resin, and halogen-substituted products, alkyl-substituted products, hydrogenated products, etc. An epoxy resin can be preferably used. Examples of such commercially available epoxy resin [A1] include “jER (registered trademark)” 1004AF, 1007, 1009P, 1010P, 4005P, 4007P, 4009P, and 4010P (above, manufactured by Mitsubishi Chemical Corporation). Among them, bisphenol A type epoxy resin or bisphenol F type epoxy resin is preferable, and bisphenol F type epoxy resin is more preferable because of a good balance of heat resistance, elastic modulus, and toughness.

In this embodiment, the epoxy resin [B1] needs to contain 30 to 50 parts by mass of trifunctional or higher amine type epoxy resin out of 100 parts by mass of the total epoxy resin. When the content of the epoxy resin [B1] is less than 30 parts by mass, the elastic modulus of the resin cured product is insufficient. Moreover, when content of epoxy resin [B1] exceeds 50 mass parts, the plastic deformation capability and toughness of resin hardened | cured material are insufficient. Of the tri- or higher functional amine-type epoxy resins, the tri-functional amine-type epoxy resins are preferable because they give the cured resin a good balance between elastic modulus and toughness. Furthermore, among the trifunctional amine type epoxy resins, aminophenol type epoxy resins are more preferable because the toughness of the cured resin is relatively high.

Examples of the epoxy resin [B1] include amine type epoxy resins such as tetraglycidyldiaminodiphenylmethane, tetraglycidyldiaminodiphenylsulfone, tetraglycidyldiaminodiphenylether, triglycidylaminophenol, triglycidylaminocresol, tetraglycidylxylylenediamine, and triglycidyl. Epoxy resins having an isocyanurate skeleton and epoxy resins selected from halogen-substituted products, alkyl-substituted products, hydrogenated products and the like are preferably used.

Examples of the tetraglycidyldiaminodiphenylmethane include “Sumiepoxy (registered trademark)” ELM434 (manufactured by Sumitomo Chemical Co., Ltd.), YH434L (manufactured by Nippon Steel Chemical Co., Ltd.), and “jER (registered trademark)” 604 (Mitsubishi Chemical Corporation). ), “Araldide (registered trademark)” MY720, MY721 (manufactured by Huntsman Advanced Materials), and the like. As the tetraglycidyl diaminodiphenyl ether, 3,3′-TGDDE (manufactured by Toray Fine Chemical Co., Ltd.) or the like can be used. As triglycidylaminophenol or triglycidylaminocresol, “Araldide (registered trademark)” MY0500, MY0510, MY0600 (manufactured by Huntsman Advanced Materials), “jER (registered trademark)” 630 (Mitsubishi Chemical Corporation) )) And the like can be used. Tetraglycidylxylylenediamine and its hydrogenated product may be “TETRAD (registered trademark)”-X, “TETRAD (registered trademark)”-C (above, manufactured by Mitsubishi Gas Chemical Co., Ltd.), etc. . As a commercial item of tetraglycidyl diaminodiphenyl sulfone, TG3DAS (manufactured by Konishi Chemical Industry Co., Ltd.) can be mentioned.

In this embodiment, since the epoxy resin [C1] gives a high elastic modulus, it is necessary to use bisphenol F type epoxy resin having a number average molecular weight of 450 or less of 10 to 40 parts by mass out of 100 parts by mass of the total epoxy resin. There is. Preferably, the epoxy resin [C1] is contained in 20 to 40 parts by mass out of 100 parts by mass of the total epoxy resin. When the compounding quantity of epoxy resin [C1] exceeds 40 mass parts, the toughness of the resin cured material obtained tends to be insufficient. Moreover, when the compounding quantity of epoxy resin [C1] is less than 10 mass parts, the viscosity of an epoxy resin composition may become high. Furthermore, the viscosity of the epoxy resin composition obtained can be made low by making the number average molecular weight of epoxy resin [C1] 450 or less. Therefore, in the prepreg manufacturing process, the epoxy resin composition is easily impregnated between the reinforcing fibers, so that the fiber content of the obtained prepreg can be improved. On the other hand, when the number average molecular weight of the epoxy resin [C1] is larger than 450, the viscosity of the epoxy resin composition tends to be high, so that the epoxy resin composition is difficult to impregnate between the reinforcing fibers in the prepreg manufacturing process. It tends to be difficult to improve the fiber content. Moreover, since the effect as a compatibilizing agent becomes large because the number average molecular weight of epoxy resin [C1] is 450 or less, it is easy to form a fine phase-separation structure. When the number average molecular weight of the bisphenol F type epoxy resin [C1] is larger than 450, the component [C1] is easily compatible with any one of the phases, so that the effect as a compatibilizer tends to be small. As a result, the phase separation structure period of the cured resin tends to increase.

In addition, the number average molecular weight as used in the field of this invention is the value calculated | required in polystyrene conversion, after melt | dissolving the epoxy resin to measure in tetrahydrofuran (THF) and measuring with a gel permeation chromatograph (GPC). Details of the measurement conditions will be described later.

The curing agent [D] is not particularly limited as long as it cures an epoxy resin, and amines such as aromatic amines and alicyclic amines, acid anhydrides, polyaminoamides, organic acid hydrazides, isocyanates And the like.

An amine curing agent is preferable because the cured resin obtained has excellent mechanical properties and heat resistance. As the amine curing agent, diaminodiphenyl sulfone and diaminodiphenylmethane which are aromatic amines, dicyandiamide or a derivative thereof which is an aliphatic amine, hydrazide compounds, and the like are used. Examples of such commercially available dicyandiamide include DICY-7 and DICY-15 (manufactured by Mitsubishi Chemical Corporation). The dicyandiamide derivative is obtained by bonding various compounds to dicyandiamide, and includes a reaction product with an epoxy resin, a reaction product with a vinyl compound or an acrylic compound.

Furthermore, it is preferable to blend dicyandiamide or a derivative thereof as a curing agent [D] as a powder into an epoxy resin composition from the viewpoint of storage stability at room temperature and viscosity stability during prepreg formation. When dicyandiamide or a derivative thereof is blended into a resin as a powder, the average particle size is preferably 10 μm or less, more preferably 7 μm or less. For example, when the reinforcing fiber bundle is impregnated into the reinforcing fiber bundle by heating and pressing in the prepreg manufacturing process, dicyandiamide or a derivative thereof having a particle size of more than 10 μm does not enter the reinforcing fiber bundle and remains on the surface of the fiber bundle. There is a case.

Further, the total amount of the curing agent [D] preferably includes an amount such that the active hydrogen groups are in the range of 0.6 to 1.0 equivalent with respect to the epoxy groups of all the epoxy resin components contained in the epoxy resin composition. More preferably, it is in the range of 0.7 to 0.9 equivalent. When the active hydrogen group is less than 0.6 equivalent, the reaction rate, heat resistance and elastic modulus of the resin cured product are insufficient, and the glass transition temperature and strength of the obtained fiber reinforced composite material may be insufficient. . When the active hydrogen group exceeds 1.0 equivalent, the reaction rate, glass transition temperature and elastic modulus of the cured resin are sufficient, but the plastic deformation ability is insufficient, so that the resulting fiber-reinforced composite material has a resistance to resistance. Impact may be insufficient.

Each curing agent may be used in combination with a curing accelerator or other epoxy resin curing agent. Examples of the curing accelerator to be combined include ureas, imidazoles, and Lewis acid catalysts.

Examples of the urea compound include N, N-dimethyl-N ′-(3,4-dichlorophenyl) urea, toluene bis (dimethylurea), 4,4′-methylenebis (phenyldimethylurea), and 3-phenyl-1 , 1-dimethylurea and the like can be used. Examples of commercially available urea compounds include DCMU99 (manufactured by Hodogaya Chemical Co., Ltd.), “Omicure (registered trademark)” 24, 52, and 94 (manufactured by CVC Specialty Chemicals, Inc.).

Examples of commercially available imidazoles include 2MZ, 2PZ, 2E4MZ (manufactured by Shikoku Kasei Co., Ltd.) and the like. Lewis acid catalysts include boron trifluoride / piperidine complex, boron trifluoride / monoethylamine complex, boron trifluoride / triethanolamine complex, boron trichloride / octylamine complex, etc. Is mentioned.

Of these, urea compounds are preferably used from the balance between storage stability and catalytic ability. The amount of the urea compound is preferably 1 to 3 parts by mass with respect to 100 parts by mass of all the epoxy resin components contained in the epoxy resin composition. When the compounding amount of the urea compound is less than 1 part by mass, the reaction does not proceed sufficiently, and the elastic modulus and heat resistance of the cured resin product tend to decrease. Moreover, when the compounding quantity of a urea compound exceeds 3 mass parts, since the self-polymerization reaction of an epoxy resin inhibits reaction with an epoxy resin and a hardening | curing agent, in addition to the toughness of a resin hardened | cured material, an elasticity modulus is also used. descend.

The second embodiment of the epoxy resin composition of the present invention comprises an epoxy resin [A2], an epoxy resin [B2], an epoxy resin [C2] and a curing agent [D], and the following conditions (1) to ( An epoxy resin composition satisfying 4):
(1) The SP value of the cured resin [B2 ′] obtained by reacting the epoxy resin [B2] with the curing agent [D] and curing the epoxy resin [A2] and [C2] is the curing agent [D]. Greater than the SP value of any of the cured resin products [A2 ′] and [C2 ′] obtained by reacting with and curing the resin;
(2) The softening point of the epoxy resin [A2] is 90 ° C. or higher, and the softening points of the epoxy resins [B2] and [C2] are both 50 ° C. or lower;
(3) Epoxy resin [C2], dicyandiamide having an active hydrogen group of 0.9 equivalent to the epoxy group of epoxy resin [C2], and 2 parts by mass of 3-parts of epoxy resin [C2] with respect to 100 parts by mass. An epoxy resin composition comprising (3,4-dichlorophenyl) -1,1-dimethylurea (hereinafter referred to as DCMU) was heated from room temperature to 130 ° C. at a rate of 2.5 ° C./min and then at 130 ° C. for 90 minutes. The elastic modulus of the cured resin obtained by reacting is 3.5 GPa or more; and (4) The cured resin obtained by reacting and curing the epoxy resins [A2] to [C2] with the curing agent [D]. However, it has a phase separation structure including [A2] rich phase and [B2] rich phase, and the phase separation structure period is 1 nm to 1 μm.

In this embodiment, the cured resin products [A2 ′], [B2 ′], and [C2 ′ obtained by reacting the epoxy resins [A2], [B2], and [C2] with the curing agent [D], respectively. ] Must satisfy the following condition.
(1) (SP value of [B2 ′]) ≧ (SP value of [A2 ′]) + 1.2
(2) (SP value of [B2 ′]) ≧ (SP value of [C2 ′]) + 1.2
Here, the SP value is a generally known solubility parameter, and is an index of solubility and compatibility. The SP value defined in the present invention is Polym. Eng. Sci. , 14 (2), 147-154 (1974), and calculated from the molecular structure based on the Fedors method. When the SP value of [B2 ′] is smaller than the value obtained by adding 1.2 to the SP value of [A2 ′], [A2] is compatible with [B2] in the obtained cured resin and is uniform. Since it becomes a structure, the elastic modulus and toughness of the resin cured product are not sufficient. Moreover, when the SP value of [B2 ′] is smaller than the value obtained by adding 1.2 to the SP value of [C2 ′], [C2], which is a compatibilizing agent, is [B2] in the obtained cured resin. ], It causes coarse phase separation of [A2] rich phase and [B2] rich phase.

In this embodiment, it is necessary that the softening point of the epoxy resin [A2] is 90 ° C. or higher and the softening points of the epoxy resins [B2] and [C2] are 50 ° C. or lower. When the epoxy resins [A2] to [C2] satisfy these requirements, it is possible to prevent [A2] from being compatible with [B2] and obtaining a uniform structure in the obtained resin cured product. Both rate and toughness are improved.

Furthermore, in this embodiment, the epoxy resin [C2], an amount of dicyandiamide in which the active hydrogen group is 0.9 equivalent to the epoxy group of the epoxy resin [C2], and 100 parts by mass of the epoxy resin [C2] The epoxy resin composition comprising 2 parts by mass of DCMU is heated from room temperature to 130 ° C. at 2.5 ° C./min and reacted at 130 ° C. for 90 minutes, and the elastic modulus of the cured resin obtained is 3. It needs to be 5 GPa or more. When the elastic modulus of the cured resin is less than 3.5 GPa, the cured resin obtained from the epoxy resin composition of the present invention cannot obtain a good elastic modulus. The epoxy resin [C2] acts as a compatibilizing agent and is a component that dissolves in both the [A2] rich phase and the [B2] rich phase, and thus the resin obtained by the high elastic modulus of the epoxy resin [C2] The elastic modulus of the cured product is increased. In particular, when the phase separation structure is a sea-island structure, it is important that the sea phase covering the island phase has a high elastic modulus. Therefore, when the epoxy resin [C2] is dissolved in the sea phase, the sea phase has a high elastic modulus. The effect by becoming becomes big. Here, the active hydrogen group means a functional group that can react with an epoxy group. Examples of the active hydrogen group include an amino group and a hydroxyl group.

Furthermore, in this embodiment, the cured resin obtained by curing the epoxy resin composition has a phase separation structure including an epoxy resin [A2] rich phase and an epoxy resin [B2] rich phase, and the phase separation structure The period must be 1 nm to 1 μm.

Since the cured resin has a phase separation structure, both the elastic modulus and toughness of the cured resin can be achieved. When the structural period is less than 1 nm, the cavitation effect cannot be exhibited, and not only the toughness is insufficient but also the elastic modulus is insufficient. In addition, when the structural period exceeds 1 μm, the structural period is large, so the crack does not progress to the island phase, but only in the sea phase, so the cavitation effect cannot be expressed and the toughness is insufficient. It becomes.

As the epoxy resin [A2], an epoxy selected from bisphenol type epoxy resins having a softening point of 90 ° C. or higher, isocyanate-modified epoxy resins, anthracene type epoxy resins and halogen-substituted products, alkyl-substituted products, hydrogenated products, etc. A resin can be preferably used.

As a commercially available product of such an epoxy resin [A2], “jER (registered trademark)” 1004AF, 1007, 1009P, 1010P, 4005P, 4007P, 4009P, 4010P (above, manufactured by Mitsubishi Chemical Corporation) as a bisphenol type epoxy resin, Examples of the isocyanate-modified epoxy resin include XAC4151 (manufactured by Asahi Kasei Chemicals Corporation).

It is preferable to use a bisphenol-type epoxy resin having a softening point of 90 ° C. or higher as the epoxy resin [A2] because it gives high toughness to the cured resin. Among these, bisphenol A type epoxy resin or bisphenol F type epoxy resin is more preferably used because of a good balance of heat resistance, elastic modulus and toughness. More preferably, it is a bisphenol F type epoxy resin because it gives a high elastic modulus. The epoxy resin [A2] is preferably contained in an amount of 20 to 50 parts by mass of 100 parts by mass of the total epoxy resin, and more preferably 30 to 50 parts by mass of 100 parts by mass of the total epoxy resin. When the content is less than 20 parts by mass, the obtained resin cured product tends to be difficult to form a phase separation structure, and the toughness tends to decrease. When the content exceeds 50 parts by mass, not only the elastic modulus and heat resistance of the cured resin product tends to be lowered, but also the viscosity of the epoxy resin composition tends to be too high. If the viscosity of the epoxy resin composition becomes too high, the epoxy resin composition may not be sufficiently impregnated between the reinforcing fibers when the prepreg is produced. For this reason, voids are generated in the obtained fiber-reinforced composite material, and the strength of the fiber-reinforced composite material may be reduced.

As the epoxy resin [B2], an amine-type epoxy resin such as tetraglycidyldiaminodiphenylmethane, tetraglycidyldiaminodiphenylether, triglycidylaminophenol, triglycidylaminocresol, tetraglycidylxylylenediamine having a softening point of 50 ° C. or less, Epoxy resins having a triglycidyl isocyanurate skeleton and epoxy resins selected from halogen-substituted products, alkyl-substituted products, hydrogenated products, and the like can be used.

Examples of the tetraglycidyldiaminodiphenylmethane include “Sumiepoxy (registered trademark)” ELM434 (manufactured by Sumitomo Chemical Co., Ltd.), YH434L (manufactured by Nippon Steel Chemical Co., Ltd.), and “jER (registered trademark)” 604 (Mitsubishi Chemical Corporation). ), “Araldide (registered trademark)” MY720, MY721 (manufactured by Huntsman Advanced Materials), etc. can be used. As the tetraglycidyl diaminodiphenyl ether, 3,3′-TGDDE (manufactured by Toray Fine Chemical Co., Ltd.) or the like can be used. As triglycidylaminophenol or triglycidylaminocresol, “Araldide (registered trademark)” MY0500, MY0510, MY0600 (manufactured by Huntsman Advanced Materials), “jER (registered trademark)” 630 (manufactured by Mitsubishi Chemical Corporation) ) Etc. can be used. As tetraglycidylxylylenediamine and hydrogenated products thereof, “TETRAD (registered trademark)”-X, “TETRAD (registered trademark)”-C (manufactured by Mitsubishi Gas Chemical Co., Inc.) and the like can be used. As an epoxy resin having a triglycidyl isocyanurate skeleton, “TEPIC (registered trademark)” B26 (Nissan Chemical Industry Co., Ltd.) or the like can be used.

The epoxy resin [B2] is preferably a tri- or higher functional amine type epoxy resin. The epoxy resin [B2] is preferably contained in 30 to 50 parts by mass out of 100 parts by mass of the total epoxy resin. When the content is less than 30 parts by mass, the obtained cured resin is unlikely to form a phase separation structure, and the elastic modulus tends to decrease. Moreover, when content exceeds 50 mass parts, the plastic deformation capability and toughness of a resin cured material are easy to fall. Of the tri- or higher functional amine-type epoxy resins, the tri-functional amine-type epoxy resins are preferable because they give the cured resin a good balance between elastic modulus and toughness. Furthermore, among the trifunctional amine type epoxy resins, aminophenol type epoxy resins have relatively high toughness and are more preferable.

As the epoxy resin [C2], a bisphenol F type epoxy resin, a bisphenol AD type epoxy resin, a bisphenol S type epoxy resin, a phenol novolak type epoxy resin having a softening point of 50 ° C. or less, halogen substitution products thereof, alkyl substitution products, An epoxy resin selected from hydrogenated products is used. Examples of commercially available epoxy resin [C2] include “Epiclon (registered trademark)” 830 and 806 (manufactured by DIC Corporation), “jER (registered trademark)” 152 (manufactured by Mitsubishi Chemical Corporation), and the like.

As the epoxy resin [C2], a bisphenol F-type epoxy resin having a number average molecular weight of 450 or less is preferable because it gives a high elastic modulus and has good compatibility with the epoxy resins [A2] and [B2]. The epoxy resin [C2] is preferably contained in an amount of 10 to 40 parts by mass out of 100 parts by mass of the total epoxy resin. More preferably, the epoxy resin [C2] is contained in an amount of 20 to 40 parts by mass out of 100 parts by mass of the total epoxy resin. When the compounding quantity of epoxy resin [C2] is less than 10 mass parts, there exists a tendency for the phase-separation structure period of the resin cured material obtained to become large. In addition, when the compounding amount of the epoxy resin [C2] exceeds 40 parts by mass, the epoxy resins [A2] and [B2] are easily compatible with each other, and it is difficult to form a phase separation structure. Rate and toughness are likely to decrease.

By setting the number average molecular weight of the epoxy resin [C2] to 450 or less, the viscosity of the resulting epoxy resin composition can be lowered. Therefore, in the prepreg manufacturing process, the epoxy resin composition is easily impregnated between the reinforcing fibers, so that the fiber content of the obtained prepreg can be improved. On the other hand, when the number average molecular weight of the epoxy resin [C2] is larger than 450, the viscosity of the epoxy resin composition tends to be high, so that the epoxy resin composition is difficult to impregnate between the reinforcing fibers in the prepreg manufacturing process. It tends to be difficult to improve the fiber content. Moreover, since the effect as a compatibilizer becomes large because the number average molecular weight of epoxy resin [C2] is 450 or less, it is easy to form a fine phase-separated structure. When the number average molecular weight of the bisphenol F-type epoxy resin [C2] is larger than 450, the component [C2] is easily compatible with any one of the phases, so that the effect as a compatibilizer tends to be small. As a result, the phase separation structure period of the cured resin tends to increase.

Examples of commercially available bisphenol F type epoxy resins having a number average molecular weight of 450 or less include “Epiclon (registered trademark)” 830 and 806 (manufactured by DIC Corporation).

The curing agent [D] is the same as the curing agent [D] described in the first embodiment.

Next, other components will be described. The epoxy resin composition of the present invention contains an epoxy resin other than the epoxy resins [A] to [C] for the purpose of adjusting viscoelasticity and improving workability or the elastic modulus and heat resistance of the cured resin. It can add in the range which does not lose the effect of invention. These may be used in combination of not only one type but also a plurality of types. Specifically, phenol novolac type epoxy resin, cresol novolac epoxy resin, resorcinol type epoxy resin, phenol aralkyl type epoxy resin, dicyclopentadiene type epoxy resin, epoxy resin having biphenyl skeleton, isocyanate modified epoxy resin, anthracene type epoxy resin Polyethylene glycol type epoxy resin, N, N′-diglycidylaniline, liquid bisphenol A type epoxy resin, and the like.

Commercially available phenol novolak type epoxy resins include “Epicoat (registered trademark)” 152, 154 (above, manufactured by Mitsubishi Chemical Corporation), “Epicron (registered trademark)” N-740, N-770, N-775 ( As mentioned above, DIC Corporation) etc. are mentioned.

Commercial products of cresol novolac type epoxy resins include “Epiclon (registered trademark)” N-660, N-665, N-670, N-673, N-695 (above, manufactured by DIC Corporation), “EOCN ( Registered trademark) "1020, 102S, 104S (Nippon Kayaku Co., Ltd.).

Specific examples of the resorcinol type epoxy resin include “Denacol (registered trademark)” EX-201 (manufactured by Nagase ChemteX Corporation).

Commercially available dicyclopentadiene type epoxy resins include “Epiclon (registered trademark)” HP7200, HP7200L, HP7200H (above, manufactured by DIC Corporation), “TACTIX (registered trademark)” 558 (manufactured by Huntsman Advanced Materials) XD-1000-1L, XD-1000-2L (Nippon Kayaku Co., Ltd.) and the like.

Examples of commercially available epoxy resins having a biphenyl skeleton include “Epicoat (registered trademark)” YX4000H, YX4000, YL6616 (manufactured by Mitsubishi Chemical Corporation), NC-3000 (manufactured by Nippon Kayaku Co., Ltd.), and the like. It is done.

Examples of commercially available isocyanate-modified epoxy resins include “AER (registered trademark)” 4152 (manufactured by Asahi Kasei E-Materials Co., Ltd.) and XAC4151 (manufactured by Asahi Kasei Chemicals Co., Ltd.) having an oxazolidone ring.

Examples of commercially available anthracene epoxy resins include YX8800 (manufactured by Mitsubishi Chemical Corporation).

Examples of commercially available polyethylene glycol type epoxy resins include “Denacol (registered trademark)” EX810, 811, 850, 851, 821, 830, 841, 861 (manufactured by Nagase ChemteX Corporation).

As a commercially available product of N, N′-diglycidylaniline, GAN (Nippon Kayaku Co., Ltd.) can be mentioned.

Examples of commercially available liquid bisphenol A type epoxy resins include “jER (registered trademark)” 828 (manufactured by Mitsubishi Chemical Corporation).

In addition, the epoxy resin composition of the present invention has a heat-solubility soluble in an epoxy resin in order to control viscoelasticity and improve mechanical properties such as tack and drape characteristics of prepreg and impact resistance of fiber reinforced composite materials. Organic particles such as plastic resins, rubber particles and thermoplastic resin particles, inorganic particles, and the like can be blended.

As the thermoplastic resin soluble in the epoxy resin, a thermoplastic resin having a hydrogen-bonding functional group that can be expected to improve the adhesion between the resin and the reinforcing fiber is preferably used. Examples of the hydrogen bondable functional group include an alcoholic hydroxyl group, an amide bond, a sulfonyl group, and a carboxyl group.

Examples of the thermoplastic resin having an alcoholic hydroxyl group include polyvinyl acetal resins such as polyvinyl formal and polyvinyl butyral; polyvinyl alcohol and phenoxy resin. Examples of the thermoplastic resin having an amide bond include polyamide, polyimide, polyamideimide, and polyvinylpyrrolidone. Examples of the thermoplastic resin having a sulfonyl group include polysulfone. Here, polyamide, polyimide and polysulfone may have a functional group such as an ether bond and a carbonyl group in the main chain. The polyamide may have a substituent on the nitrogen atom of the amide group. Examples of the thermoplastic resin having a carboxyl group include polyester, polyamide, and polyamideimide.

Commercially available thermoplastic resins soluble in epoxy resins and having hydrogen-bonding functional groups include: Denkabutyral as a polyvinyl acetal resin; “Denkapoval (registered trademark)” as a polyvinyl alcohol resin (manufactured by Denki Kagaku Kogyo Co., Ltd.) , “Vinylec (registered trademark)” (manufactured by JNC); “Macromelt (registered trademark)” (manufactured by Henkel Co., Ltd.), “Amilan (registered trademark)” CM4000 (manufactured by Toray Industries, Inc.); polyimide As “Ultem (registered trademark)” (manufactured by Subic Innovative Plastics), “Aurum (registered trademark)” (manufactured by Mitsui Chemicals), “Vespel (registered trademark)” (manufactured by DuPont); “Victrex (registered trademark)” (manufactured by Victrex); Trademark) "(Solvay manufactured Advanced Polymers, Inc.), polyvinylpyrrolidone as" Luviskol (registered trademark) "(BASF Japan Ltd. can be exemplified, Ltd.).

In addition, the acrylic resin has high compatibility with the epoxy resin and is preferably used for controlling the viscoelasticity. Commercially available acrylic resins include “Dianar (registered trademark)” BR series (Mitsubishi Rayon Co., Ltd.), “Matsumoto Microsphere (registered trademark)” M, M100, M500 (Matsumoto Yushi Seiyaku Co., Ltd.) ) And the like.

As the rubber particles, cross-linked rubber particles, and core-shell rubber particles obtained by graft polymerization of a different polymer on the surface of the cross-linked rubber particles are preferably used from the viewpoint of handleability and the like.

Examples of commercially available core-shell rubber particles include “Paraloid (registered trademark)” EXL-2655, EXL-2611, and EXL-3387 (produced by Rohm and Haas Co., Ltd.) made of a butadiene / alkyl methacrylate / styrene copolymer. "STAPHYLOID (registered trademark)" AC-3355, TR-2122 (manufactured by Ganz Corporation), "NANOSTRENGTH (registered trademark)" M22, 51, 52, 53 made of an acrylic ester / methacrylic ester copolymer (Manufactured by Arkema Co., Ltd.), “Kane Ace (registered trademark)” MX series (manufactured by Kaneka Corporation) and the like can be used.

As the thermoplastic resin particles, polyamide particles or polyimide particles are preferably used. As commercially available polyamide particles, SP-500 (manufactured by Toray Industries, Inc.), “Orgazol (registered trademark)” (manufactured by Arkema Co., Ltd.) and the like can be used.

In the present invention, at least one block copolymer [E] (hereinafter abbreviated to block copolymer [E]) selected from the group consisting of SBM, BM, and MBM Further, it is effective to improve toughness and impact resistance while maintaining excellent heat resistance of the epoxy resin composition.

Here, the above-mentioned S, B, and M mean each block defined below. Each block represented by S, B and M is linked directly by a covalent bond or through some chemical structure.

In addition, when the block copolymer is SBM, any block of S, B, and M is used. When the block copolymer is BM or MBM, B and M are used. It is preferable from the viewpoint of improving toughness that any of the blocks is compatible with the epoxy resin.

Block M is a block made of a polymethyl methacrylate homopolymer or a copolymer containing 50% by mass or more of methyl methacrylate. The block M is preferably composed of 60% by mass or more of syndiotactic PMMA (polymethyl methacrylate).

Block B is a block that is incompatible with block M and has a glass transition temperature of 20 ° C. or lower. The glass transition temperature of the block B is a dynamic viscoelasticity measuring device (RSAII: manufactured by Rheometrics, Inc. or rheometer ARES: whether the epoxy resin composition or the block copolymer [E] alone is used. (Manufactured by TA Instruments) can be measured by the DMA method. That is, the measurement sample is made into a plate having a thickness of 1 mm, a width of 2.5 mm, and a length of 34 mm, and the period for applying stress is measured while sweeping it at a temperature of −100 to 250 ° C., and its tan δ value is measured. Is the glass transition temperature of block B. Here, the sample is manufactured as follows. When an epoxy resin composition is used, the uncured resin composition is defoamed in vacuum, and then 130 mm in a mold set to a thickness of 1 mm by a 1 mm thick “Teflon (registered trademark)” spacer. By curing at a temperature of 2 ° C. for 2 hours, a cured resinous plate-like resin can be obtained. When a block copolymer is used alone, a void-free plate is prepared using a biaxial extruder. These plates can be evaluated by cutting them into the above size with a diamond cutter.

The glass transition temperature of block B is 20 ° C. or lower, preferably 0 ° C. or lower, more preferably −40 ° C. or lower. The glass transition temperature is preferably as low as possible from the viewpoint of toughness. However, if the glass transition temperature is lower than −100 ° C., there may be a problem in workability such as a roughened cutting surface when a fiber-reinforced composite material is obtained.

The block B is preferably an elastomer block. The monomer constituting such an elastomer block can be selected from butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene and 2-phenyl-1,3-butadiene.

The block B is preferably selected from polydienes, particularly polybutadiene, polyisoprene and random copolymers thereof, or partially or completely hydrogenated polydienes from the viewpoint of toughness. Such partially or fully hydrogenated polydienes can be made according to conventional hydrogenation methods. Of the dienes listed above, it is more preferred to use 1,4-polybutadiene (glass transition temperature of about -90 ° C.) having the lowest glass transition temperature. This is because the use of the block B having a lower glass transition temperature is advantageous from the viewpoint of impact resistance and toughness.

As the monomer constituting the elastomer block B, alkyl (meth) acrylate can also be used. Specific examples include ethyl acrylate (−24 ° C.), butyl acrylate (−54 ° C.), 2-ethylhexyl acrylate (−85 ° C.), hydroxyethyl acrylate (−15 ° C.), and 2-ethylhexyl methacrylate (−10 ° C.). Can be mentioned. Here, the numerical value shown in parentheses after the name of each acrylate is the glass transition temperature of the block B obtained when each acrylate is used. Of these, butyl acrylate is preferably used. These acrylates are incompatible with the block M containing 50% by mass or more of methyl methacrylate. The block B is more preferably selected from poly 1,4-butadiene, polybutyl acrylate and poly (2-ethylhexyl acrylate), and more preferably poly 1,4-butadiene or poly (butyl acrylate).

Block S is a block that is incompatible with blocks B and M and has a glass transition temperature higher than that of block B. The glass transition temperature or melting point of the block S is preferably 23 ° C. or higher, and more preferably 50 ° C. or higher. Examples of monomers constituting the block S include aromatic vinyl compounds such as styrene, α-methylstyrene or vinyl toluene; alkyl esters of (meth) acrylic acid having an alkyl chain having 1 to 18 carbon atoms. it can.

The blending amount of the block copolymer [E] is preferably 1 to 10 parts by mass, more preferably 100 parts by mass with respect to 100 parts by mass of all epoxy resin components, from the viewpoint of mechanical properties and compatibility with the composite production process. Is 2 to 7 parts by mass. When the blending amount of the block copolymer [E] is less than 1 part by mass, the effect of improving the toughness and plastic deformation ability of the cured resin is small, and the impact resistance of the fiber-reinforced composite material may be lowered. When it exceeds 10 parts by mass, the elastic modulus of the cured resin is lowered, the mechanical properties of the fiber-reinforced composite material are lowered, and the viscosity of the epoxy resin composition is increased, so that the handleability may be deteriorated.

When the triblock copolymer MBM is used as the block copolymer [E], the two blocks M of the triblock copolymer MBM may be the same as or different from each other. Also, the molecular weight can be different due to the same monomer.

When the triblock copolymer MBM and the diblock copolymer BM are used in combination as the block copolymer [E], the block M of the triblock copolymer MBM is diblock copolymer. The M block of the polymer BM may be the same as or different from the M block, and the block B of the MBM triblock may be the same as or different from the diblock copolymer BM.

When the triblock copolymer SBM and the diblock copolymer BM and / or the triblock copolymer MBM are used in combination as the block copolymer [E], the triblock The block M of the copolymer SBM, each block M of the triblock copolymer MBM, and the block M of the diblock copolymer BM may be the same as or different from each other. The blocks B of the triblock copolymer SBM, the triblock copolymer MBM, and the diblock copolymer BM may be the same as or different from each other.

The block copolymer [E] can be produced by anionic polymerization. For example, it can be produced by the methods described in European Patent No. EP 524,054 and European Patent No. EP 749,987.

Specific examples of the triblock copolymer MBM include Nanostrength M22 (manufactured by Arkema) consisting of methyl methacrylate-butyl acrylate-methyl methacrylate and Nanostrength M22N (manufactured by Arkema) having polar functional groups. Can be mentioned. Specific examples of the triblock copolymer SBM are Nanostrength 123, Nanostrength 250, Nanostrength 012, Nanostrength E20, Nanostrength E40 (manufactured by Arkema, Inc.) made of Arkema, which is made of styrene-butadiene-methyl methacrylate. Is mentioned.

In the case where the block copolymer [E] is contained, even if the epoxy resins [A] to [C] and the block copolymer [E] are uniformly compatible with each other before curing, the curing process , Spinodal decomposition tends to form a phase separation structure including at least three phases of an epoxy resin [A] rich phase, an epoxy resin [B] rich phase, and a block copolymer [E] rich phase.

The epoxy resin composition comprising the epoxy resins [A2] to [C2], the curing agent [D] and the block copolymer [E] has a cured resin obtained by the epoxy resin [A2] rich phase, the epoxy resin [B2 ] Having a phase separation structure including a rich phase and a block copolymer [E] rich phase, an epoxy resin [A2] rich phase, an epoxy resin [B2] rich phase, and a block copolymer [E] rich phase The phase separation structure period is preferably 1 nm to 1 μm.

The epoxy resin composition comprising the epoxy resins [A1] to [C1], the curing agent [D] and the block copolymer [E] has a cured resin obtained by the epoxy resin [A1] rich phase and the epoxy resin [B1. ] Having a phase separation structure containing a rich phase and a block copolymer [E] rich phase, and comprising an epoxy resin [A1] rich phase, an epoxy resin [B1] rich phase, and a block copolymer [E] rich phase. The phase separation structure period is preferably 1 nm to 5 μm, and the phase separation period of the block copolymer [E] rich phase is more preferably 1 nm to 1 μm.

When the phase separation structure period of the epoxy resin [A] rich phase and the epoxy resin [B] rich phase is too small, one or more of the following adjustment methods are within the range not impairing the object of the present invention. By carrying out the step, the phase separation structure period can be increased.
(1) The blending ratio of the epoxy resin [C] to the total epoxy resin is reduced.
(2) Increase the softening point of the epoxy resin [A].
(3) Lower the softening point of the epoxy resin [B].
(4) Increase the blending ratio of both epoxy resins [A] and [B].

In addition, the phase separation structure period of the epoxy resin [A] rich phase and the epoxy resin [B] rich phase is within a range that does not impair the object of the present invention, and one or more of the following adjustment methods are performed. Therefore, it can be reduced.
(1) Increase the blending ratio of the epoxy resin [C] to the total epoxy resin.
(2) Lower the softening point of the epoxy resin [A].
(3) Increase the softening point of the epoxy resin [B].
(4) The blending ratio of both epoxy resins [A] and [B] is reduced.

In addition, the phase separation structure period of the block copolymer [E] rich phase can be reduced by performing one or more of the following adjustment methods within a range that does not impair the object of the present invention. it can.
(1) The blending ratio of the block copolymer [E] is reduced.
(2) Lower the softening point of the epoxy resin [A].
(3) Increase the compounding ratio of the epoxy resin [B].

In addition, the phase separation structure period of the block copolymer [E] rich phase can be increased by performing one or more of the following adjustment methods within a range that does not impair the object of the present invention. .
(1) Increase the blending ratio of the block copolymer [E].
(2) Increase the softening point of the epoxy resin [A].
(3) The blending ratio of the epoxy resin [B] is reduced.

When the epoxy resin composition of the present invention is used as a matrix resin for a prepreg, the viscosity at 80 ° C. of the epoxy resin composition is preferably 0.5 to 200 Pa · s from the viewpoint of processability such as tack and drape. . When the viscosity at 80 ° C. of the epoxy resin composition is less than 0.5 Pa · s, the produced prepreg is difficult to maintain its shape, and the prepreg may be cracked. Moreover, many resin flows are produced at the time of molding of the fiber reinforced composite material, and there is a possibility that the reinforced fiber content varies. Further, when the viscosity at 80 ° C. exceeds 200 Pa · s, the epoxy resin composition may not be sufficiently impregnated between the reinforcing fibers when the prepreg is produced. For this reason, voids are generated in the obtained fiber-reinforced composite material, and the strength of the fiber-reinforced composite material may be reduced. The viscosity at 80 ° C. of the epoxy resin composition is more preferably in the range of 5 to 50 Pa · s because the resin can easily be impregnated between the reinforcing fibers in the prepreg manufacturing process and a prepreg having a high fiber content can be manufactured. . The viscosity can be lowered by performing one or more of the following methods (1) to (2) within the range not impairing the object of the present invention, and the following (3) to (4) The viscosity can be increased by performing one or more methods.
(1) Use epoxy resin [A] and / or [B] having a low softening point.
(2) Increase the amount of the epoxy resin [C].
(3) An epoxy resin [A] and / or [B] having a high softening point is used.
(4) A thermoplastic resin is blended.

Here, the viscosity is a dynamic viscoelasticity measuring device (Rheometer RDA2: manufactured by Rheometrics or Rheometer ARES: manufactured by TA Instruments), a parallel plate having a diameter of 40 mm, and a temperature rising rate of 1. It refers to the complex viscoelastic modulus η ^* obtained by simply raising the temperature at 5 ° C./min and measuring at a frequency of 0.5 Hz and a gap of 1 mm.

In the epoxy resin composition of the present invention, the elastic modulus of the cured resin product is preferably in the range of 3.8 to 5.0 GPa. More preferably, it is 4.0 to 5.0 GPa. When the elastic modulus is less than 3.8 GPa, the static strength of the obtained fiber-reinforced composite material may be lowered. When this elastic modulus exceeds 5.0 GPa, the plastic deformation ability of the obtained fiber reinforced composite material tends to be low, and the impact strength of the fiber reinforced composite material may be reduced. The method for measuring the elastic modulus will be described in detail later.

The elastic modulus of the cured resin can be improved by performing one or more of the following methods within a range that does not impair the object of the present invention.
(1) A bisphenol F type epoxy resin having a high elastic modulus is used as the epoxy resin [A].
(2) Increase the compounding quantity of epoxy resin [B].
(3) An amine type epoxy is used as the epoxy resin [B], and an aminophenol type epoxy resin having a high elastic modulus is used.
(4) A bisphenol F type epoxy resin is used as the epoxy resin [C].

The curing temperature and curing time for obtaining the cured resin are selected according to the curing agent and catalyst to be blended. For example, in the case of a curing agent system in which dicyandiamide and DCMU are combined, conditions for curing at a temperature of 130 to 150 ° C. for 90 minutes to 2 hours are preferable, and when diaminodiphenyl sulfone is used, a temperature of 180 ° C. for 2 to 3 hours. Conditions for curing are preferred.

The resin toughness value of the cured resin obtained by curing the epoxy resin composition of the present invention is preferably 1.1 MPa · m ^0.5 or more. More preferably, it is 1.3 MPa · m ^0.5 or more. If the resin toughness value is less than 1.1 MPa · m ^0.5 , the impact resistance of the resulting fiber-reinforced composite material may be reduced. The method for measuring the resin toughness value will be described in detail later.

The resin toughness value can be improved by performing one or more of the following methods within a range that does not impair the object of the present invention.
(1) An epoxy resin [A] and / or [B] having a large number average molecular weight is used.
(2) Increase the compounding quantity of epoxy resin [A].
(3) A block copolymer [E] is blended.

For preparing the epoxy resin composition of the present invention, a kneader, a planetary mixer, a three-roll extruder, a twin-screw extruder, or the like is preferably used. The epoxy resins [A] to [C] are added, and the temperature of the epoxy resin mixture is increased to an arbitrary temperature of 130 to 180 ° C. while stirring to dissolve the epoxy resins [A] to [C] uniformly. At this time, other components such as the block copolymer [E] other than the curing agent [D] and the curing accelerator may be added and kneaded together. Thereafter, while stirring, the temperature is preferably lowered to 100 ° C. or lower, more preferably 80 ° C. or lower, and further preferably 60 ° C. or lower, and the curing agent [D] and the curing accelerator are added, kneaded and dispersed. This method is preferably used because an epoxy resin composition having excellent storage stability can be obtained.

Next, the fiber reinforced composite material will be described. The fiber-reinforced composite material containing the cured product of the epoxy resin composition of the present invention as a matrix resin can be obtained by impregnating the epoxy resin composition of the present invention into a reinforcing fiber and then curing.

The reinforcing fiber used in the present invention is not particularly limited, and glass fiber, carbon fiber, aramid fiber, boron fiber, alumina fiber, silicon carbide fiber and the like are used. Two or more of these fibers may be mixed and used. Among these, it is preferable to use carbon fibers from which a lightweight and highly rigid fiber-reinforced composite material can be obtained. Among these, carbon fibers having a tensile modulus of 230 to 800 GPa are preferably used, and carbon fibers having a tensile modulus of 280 GPa are more preferably used. When carbon fibers having a high elastic modulus of 230 to 800 GPa are combined with the epoxy resin composition of the present invention, the effects of the present invention are particularly prominent, and a fiber-reinforced composite material having good impact resistance tends to be obtained. There is.

The form of the reinforcing fiber is not particularly limited, and for example, long fibers arranged in one direction, tows, woven fabrics, mats, knits, braids, short fibers chopped to a length of less than 10 mm, and the like are used. The term “long fiber” as used herein refers to a single fiber or fiber bundle that is substantially continuous by 10 mm or more. A short fiber is a fiber bundle cut to a length of less than 10 mm. In particular, for applications requiring high specific strength and specific elastic modulus, an array in which reinforcing fiber bundles are aligned in a single direction is most suitable.

The method for producing the fiber-reinforced composite material of the present invention is not particularly limited, but includes a prepreg lamination molding method, a resin transfer molding method, a resin film infusion method, a hand layup method, a sheet molding compound method, and a filament winding method. , Pultrusion method, etc.

The resin transfer molding method is a method in which a reinforcing fiber base material is directly impregnated with a liquid thermosetting resin composition and then cured. Since this method does not go through an intermediate such as a prepreg, it has the potential to reduce molding costs, and can be preferably used for structural materials such as spacecraft, aircraft, railway vehicles, automobiles, and ships.

The prepreg laminate molding method is to form and / or laminate a prepreg impregnated with a thermosetting resin composition on a reinforcing fiber substrate, and then heat cure the resin while applying pressure to the shaped product and / or laminate. Thus, a fiber reinforced composite material is obtained.

In the filament winding method, 1 to several tens of rovings of reinforcing fibers are arranged, wound around a rotating mold (mandrel) while impregnated with a thermosetting resin composition, tensioned to a predetermined thickness and wound at a predetermined angle, This is a method of demolding after curing.

In the pultrusion method, reinforcing fibers are continuously passed through an impregnation tank filled with a liquid thermosetting resin composition to impregnate the thermosetting resin composition, and then continuously by a squeeze die and a heating mold by a tension machine. This is a method of forming and curing while pulling out. Since this method has an advantage that a fiber reinforced composite material can be continuously formed, it is used for manufacturing reinforced fiber plastics (FRP) such as fishing rods, rods, pipes, sheets, antennas, and building structures.

Among these, the prepreg laminate molding method is preferable because the obtained fiber-reinforced composite material is excellent in rigidity and strength.

A preferred prepreg includes the epoxy resin composition of the present invention and reinforcing fibers. Such a prepreg can be obtained by impregnating the reinforcing fiber substrate with the epoxy resin composition of the present invention. Examples of the impregnation method include a wet method and a hot melt method (dry method).

In the wet method, after immersing the reinforcing fiber in a solution in which the epoxy resin composition is dissolved in a solvent such as methyl ethyl ketone or methanol, the reinforcing fiber is pulled up, and the solvent is evaporated from the reinforcing fiber using an oven or the like. This is a method of impregnating a reinforcing fiber. The hot melt method is a method in which a reinforcing fiber is impregnated directly with an epoxy resin composition whose viscosity is reduced by heating, or a film in which an epoxy resin composition is coated on a release paper is prepared, and then both sides of the reinforcing fiber are prepared. Alternatively, it is a method of impregnating a reinforcing fiber with a resin by overlapping the film from one side and heating and pressing. Since there is no solvent remaining in the prepreg, it is preferable to use a hot melt method.

The amount of reinforcing fibers per unit area of the prepreg is preferably 70 to 200 g / m ² . When the amount of reinforcing fibers is less than 70 g / m ² , it is necessary to increase the number of laminated layers in order to obtain a predetermined thickness when forming a fiber reinforced composite material, and the laminating work may be complicated. On the other hand, when the amount of reinforcing fibers exceeds 200 g / m ² , the prepreg drapability tends to deteriorate. The mass content of the reinforcing fiber in the prepreg is preferably 60 to 90% by mass, more preferably 65 to 85% by mass, and further preferably 70 to 80% by mass. If the mass content of the reinforced fiber is less than 60% by mass, the resin ratio is too large, so that it is difficult to obtain the advantages of the fiber reinforced composite material having excellent specific strength and specific elastic modulus, or when the fiber reinforced composite material is cured. The calorific value may be too high. Further, when the mass content of the reinforcing fiber exceeds 90% by mass, the resin is difficult to be impregnated, so that the obtained fiber-reinforced composite material may have a lot of voids.

In the prepreg laminate molding method, as a method of applying heat and pressure, a press molding method, an autoclave molding method, a bagging molding method, a wrapping tape method, an internal pressure molding method, or the like can be appropriately used.

The autoclave molding method is a method in which a prepreg is laminated on a tool plate having a predetermined shape, covered with a bagging film, and pressurized and heat-cured while degassing the inside of the laminate. Since the fiber orientation can be precisely controlled and the generation of voids is small, a molded article having excellent mechanical properties and high quality can be obtained. The pressure applied during molding is preferably 0.3 to 1.0 MPa. The molding temperature is preferably in the range of 90 to 200 ° C.

The wrapping tape method is a method of forming a tubular body made of a fiber reinforced composite material by winding a prepreg around a mandrel or the like. This is a preferable method when producing rod-shaped bodies such as golf shafts and fishing rods. More specifically, the prepreg is wound around a mandrel, and in order to fix and apply pressure to the prepreg, a wrapping tape made of a thermoplastic film is wound around the wound prepreg while applying tension, and pressure is applied to the prepreg. After the resin is heat-cured in an oven, the mandrel is withdrawn to obtain a tubular body. The tension for winding the wrapping tape is preferably 20 to 78N. The molding temperature is preferably in the range of 80 to 200 ° C.

Also, the internal pressure molding method is to set a preform in which a prepreg is wound on an internal pressure applying body such as a tube made of a thermoplastic resin in a mold, and then introduce a high pressure gas into the internal pressure applying body to apply pressure. At the same time, the mold is heated and molded. This method is preferably used when molding a complicated shape such as a golf shaft, a bad, a racket such as tennis or badminton. The pressure applied during molding is preferably 0.1 to 2.0 MPa. The molding temperature is preferably in the range of room temperature to 200 ° C, more preferably in the range of 80 to 180 ° C.

The cured product of the epoxy resin composition of the present invention and a fiber-reinforced composite material containing reinforcing fibers are preferably used for sports applications, general industrial applications, and aerospace applications. More specifically, in sports applications, it is preferably used for golf shafts, fishing rods, tennis or badminton rackets, hockey sticks, ski poles, and the like. In addition, in general industrial applications, structural materials for moving bodies such as automobiles, bicycles, ships and railway vehicles, drive shafts, leaf springs, windmill blades, pressure vessels, flywheels, paper rollers, roofing materials, cables, and repair reinforcement materials Etc. are preferably used.

The tubular body made of fiber reinforced composite material obtained by curing the prepreg of the present invention into a tubular shape can be preferably used for golf shafts, fishing rods and the like.

Hereinafter, the present invention will be described in more detail with reference to examples. Various physical properties were measured by the following methods. These physical properties were measured in an environment at a temperature of 23 ° C. and a relative humidity of 50% unless otherwise specified.

(1) Preparation of epoxy resin composition In a kneader, a predetermined amount of components other than a curing agent and a curing accelerator are added, and while kneading, the temperature is raised to 150 ° C., and kneaded at 150 ° C. for 1 hour to be transparent. A viscous liquid was obtained. After the viscous liquid was cooled to 70 ° C. while being cooled, a predetermined amount of a curing agent and a curing accelerator was added and further kneaded to obtain an epoxy resin composition. The compounding ratios of the examples and comparative examples are as shown in Tables 2 to 5. Table 1 shows the SP value, softening point, and number average molecular weight of the epoxy resin used.

<Epoxy resin ([A1] or [A2])>
-Bisphenol A type epoxy resin ("jER (registered trademark)" 1007, epoxy equivalent: 1925, manufactured by Mitsubishi Chemical Corporation)
-Bisphenol F type epoxy resin ("jER (registered trademark)" 4007P, epoxy equivalent: 2270, manufactured by Mitsubishi Chemical Corporation)
-Bisphenol F type epoxy resin ("jER (registered trademark)" 4010P, epoxy equivalent: 4400, manufactured by Mitsubishi Chemical Corporation)
<Epoxy resin ([B1] or [B2])>
Tetraglycidyl diaminodiphenyl methane (“Sumiepoxy (registered trademark)” ELM434, manufactured by Sumitomo Chemical Co., Ltd., epoxy equivalent: 125)
Triglycidyl-p-aminophenol ("jER (registered trademark)" jER630, epoxy equivalent: 98, manufactured by Mitsubishi Chemical Corporation)
Triglycidyl-p-aminophenol ("Araldide (registered trademark)" MY0500, epoxy equivalent: 110, manufactured by Heitzmann Advanced Material Co., Ltd.)
・ 3,3′-tetraglycidyldiaminodiphenyl ether (TG3DDE, epoxy equivalent: 122, manufactured by Toray Fine Chemical Co., Ltd.)
<Epoxy resin ([B1])>
・ 3,3′-tetraglycidyldiaminodiphenylsulfone (TG3DAS, epoxy equivalent: 136, manufactured by Konishi Chemical Co., Ltd.)
<Epoxy resin ([C1] or [C2])>
・ Bisphenol F type epoxy resin ("Epiclon (registered trademark)" 830, epoxy equivalent: 170, manufactured by DIC Corporation)
<Epoxy resin ([C1])>
・ Phenol novolac resin “jER (registered trademark)” 152 (manufactured by Mitsubishi Chemical Corporation)
<Curing agent ([D])>
Dicyandiamide (curing agent, DICY7, manufactured by Mitsubishi Chemical Corporation).

<Block copolymer [E]>
SBM copolymer (“Nanostrength®” E40: S is polystyrene (Tg: about 90 ° C.), B is poly 1,4-butadiene (Tg: about −90 ° C.), M is poly Block copolymer consisting of methyl methacrylate (Tg: about 130 ° C., manufactured by Arkema Co., Ltd.)
MBM copolymer ("Nanostrength (registered trademark)" M22N: B is polybutyl acrylate (Tg: about -50 ° C), M is polar methacrylate having higher SP value than methyl methacrylate and methyl methacrylate A block copolymer comprising a copolymer of group-containing monomers (Tg: about 130 ° C., manufactured by Arkema Co., Ltd.).

<Other ingredients>
・ Polyfunctional epoxy resin ("jER (registered trademark)" 1031S, epoxy equivalent: 200, manufactured by Mitsubishi Chemical Corporation)
-Bisphenol A type epoxy resin ("jER (registered trademark)" 1001, epoxy equivalent: 470, manufactured by Mitsubishi Chemical Corporation)
-Bisphenol F type epoxy resin ("jER (registered trademark)" 4004P, epoxy equivalent: 880, manufactured by Mitsubishi Chemical Corporation)
・ Glycidylphthalimide ("Denacol (registered trademark)" EX731, epoxy equivalent: 216, manufactured by Nagase ChemteX Corporation)
Polyethylene glycol type epoxy resin (“Denacol (registered trademark)” EX821, epoxy equivalent: 185, manufactured by Nagase ChemteX Corporation)
・ N, N'-Diglycidylaniline (GAN, epoxy equivalent: 125, Nippon Kayaku Co., Ltd.)
・ "Vinylec (registered trademark)" PVF-K (polyvinyl formal), manufactured by JNC Corporation)
DCMU99 (3- (3,4-dichlorophenyl) -1,1-dimethylurea, curing accelerator, manufactured by Hodogaya Chemical Co., Ltd.)

(2) Number average molecular weight measurement “HLC (registered trademark)” 8220GPC (manufactured by Tosoh Corporation) as a measuring device, UV-8000 (254 nm) as a detector, and TSK-G4000H (manufactured by Tosoh Corporation) as a column. Using. The epoxy resin to be measured was dissolved in THF at a concentration of 0.1 mg / ml, and this was measured at a flow rate of 1.0 ml / min and a temperature of 40 ° C. The retention time of the measurement sample was converted to molecular weight using the retention time of the polystyrene calibration sample, and the number average molecular weight was determined.

(3) Elastic Modulus of Resin Cured Product After defoaming the epoxy resin composition in vacuum, 130% unless otherwise specified in a mold set to 2 mm thickness with a 2 mm thick Teflon (registered trademark) spacer. Curing was performed at a temperature of 90 ° C. for 90 minutes to obtain a plate-shaped resin cured product having a thickness of 2 mm. From this cured resin, a test piece having a width of 10 mm and a length of 60 mm was cut out, an Instron universal testing machine (manufactured by Instron) was used, the span was set to 32 mm, the crosshead speed was set to 100 mm / min, and JIS K7171 (1994). According to the above, three-point bending was performed and the elastic modulus was measured. The average value of the values measured with the number of samples n = 5 was taken as the elastic modulus value.

(4) Measurement of resin toughness value of cured resin product After defoaming the epoxy resin composition in vacuum, it was particularly refused in a mold set to 6 mm thickness with a 6 mm thick Teflon (registered trademark) spacer. Unless otherwise specified, it was cured at a temperature of 130 ° C. for 90 minutes to obtain a plate-shaped resin cured product having a thickness of 6 mm. A test piece having a width of 12.7 mm and a length of 150 mm was cut out from the cured resin, processed according to ASTM D5045 (1999), and measured using an Instron universal tester (Instron). It was. The initial precrack was introduced into the test piece by applying a razor blade cooled to liquid nitrogen temperature to the test piece and applying an impact to the razor with a hammer. Here, the resin toughness value refers to the critical stress strength of deformation mode I (opening type). The average value of the values measured with the number of samples n = 5 was defined as the resin toughness value.

(5) Measurement of structural period After the resin cured product obtained in (4) was dyed, it was cut into thin sections and a transmission electron image was obtained under the following conditions using a transmission electron microscope (TEM). As the staining agent, OsO ₄ and RuO ₄ were properly used according to the resin composition so that the morphology was sufficiently contrasted.
Apparatus: H-7100 transmission electron microscope (manufactured by Hitachi, Ltd.)
Acceleration voltage: 100 kV
Magnification: 10,000 times The structure period of [A1] or [A2] rich phase, [B1] or [B2] rich phase, and [E] rich phase was observed from the transmission electron image. Depending on the type and ratio of each component, the phase separation structure of the resin cured product forms a biphasic continuous structure or a sea-island structure, and thus was measured as follows.

When the phase separation structure is a biphasic continuous structure, draw three straight lines of a predetermined length on the micrograph, extract the intersection of the straight line and the phase interface, measure the distance between the adjacent intersections, These number average values were used as the structure period. The predetermined length is set as follows based on a micrograph. When the structural period is expected to be on the order of 0.01 μm (0.01 μm or more and less than 0.1 μm), a sample photograph was taken at a magnification of 20,000 times, and a length of 20 mm drawn on the photograph (1 μm on the sample) Was defined as a predetermined straight line length. Similarly, when the phase separation structure period is expected to be on the order of 0.1 μm (0.1 μm or more and less than 1 μm), a photograph is taken at a magnification of 2,000 times and a length of 20 mm on the photograph (10 μm on the sample) The length) is a predetermined length of the straight line. When the phase separation structure period is expected to be on the order of 1 μm (1 μm or more and less than 10 μm), a photograph is taken at a magnification of 200 times, and a length of 20 mm on the photograph (a length of 100 μm on the sample) is defined as a predetermined straight line length. did. If the measured phase separation structure period was out of the expected order, it was measured again at a magnification corresponding to the corresponding order.

When the phase separation structure is a sea-island structure, three predetermined regions on the micrograph were selected at random, the island phase size in the region was measured, and the number average value thereof was taken as the structure period. The size of the island phase refers to the length of the shortest distance line drawn from the phase interface to one phase interface through the island phase. Even when the island phase is an ellipse, an indeterminate shape, or a circle or ellipse of two or more layers, the shortest distance passing through the island phase from the phase interface to one phase interface is defined as the island phase size. The predetermined region is set as follows based on a micrograph. When the phase separation structure period is expected to be on the order of 0.01 μm (0.01 μm or more and less than 0.1 μm), a photograph of the sample was taken at a magnification of 20,000 times, and an area of 4 mm square on the photograph (0 on the sample) .2 μm square area) was defined as a predetermined area. Similarly, when the phase separation structure period is expected to be on the order of 0.1 μm (0.1 μm or more and less than 1 μm), a sample photograph is taken at a magnification of 2,000 times, and a 4 mm square area (sample) The upper 2 μm square area) was defined as a predetermined area. When the phase separation structure period is expected to be on the order of 1 μm (1 μm or more and less than 10 μm), a photograph was taken at a magnification of 200 times, and an area of 4 mm square on the photograph (an area of 20 μm square on the sample) was defined as a predetermined area. If the measured phase separation structure period was out of the expected order, it was measured again at a magnification corresponding to the corresponding order.

(6) Preparation of prepreg The epoxy resin composition was applied onto release paper using a reverse roll coater to prepare a resin film. Next, both surfaces of carbon resin “TORAYCA (registered trademark)” T800SC-24K (manufactured by Toray Industries, Inc., tensile elastic modulus: 294 GPa, tensile strength: 5880 MPa) in which the two resin films are aligned in one direction in a sheet shape. The carbon fiber was impregnated with heat and pressure to impregnate the carbon fiber, and a T800SC unidirectional prepreg having a carbon fiber mass of 125 g / m ² per unit area and a fiber mass content of 75 mass% was produced. Further, in the same manner as described above except that T700SC-24K (manufactured by Toray Industries, Inc., tensile elastic modulus: 230 GPa, tensile strength: 4900 MPa) was used as the carbon fiber, the mass of carbon fiber per unit area was 125 g / m ² , A unidirectional prepreg using T700SC having a fiber mass content of 75% by mass was also produced.

(7) Production of Unidirectional Laminate Plate The unidirectional prepreg produced in (6) above was laminated in 20 ply with the fiber direction aligned. Next, the laminated prepreg was covered with a nylon film so that there was no gap. This was cured by heating and pressing at 135 ° C. and an internal pressure of 588 kPa for 2 hours in an autoclave to produce a unidirectional laminate.

(8) Fabrication of cylindrical body made of fiber reinforced composite material for cylindrical Charpy impact test By the following operations (a) to (e), a unidirectional prepreg using T800SC was obtained with a fiber direction of 45 ° with respect to the cylindrical axis direction. 3ply is laminated alternately so that the angle is 45 °, and one-way prepreg using T800SC is laminated, 3ply is laminated so that the fiber direction is parallel to the cylindrical axis direction, and the inner diameter is 6.3 mm. A tubular material was made. As the mandrel, a stainless steel round bar having a diameter of 6.3 mm and a length of 1000 mm was used.

(A) Two prepregs having a rectangular shape of 104 mm length and 800 mm width (so that the fiber axis direction is 45 degrees with respect to the long side direction) from the unidirectional prepreg using T800SC produced according to (6) above. Was cut out. The two cut prepreg fibers were bonded to each other so that the directions of the fibers intersected each other and shifted by 10 mm (half the mandrel half circumference) in the short side direction.

(B) The bonded prepreg was wound on the mandrel subjected to the mold release treatment so that the long side of the rectangle of the prepreg and the mandrel axis direction were the same direction.

(C) On top of that, a unidirectional prepreg using T800SC produced according to (6) above was cut into a rectangular shape with a length of 114 mm and a width of 800 mm (the long side direction is the fiber axis direction), and the fiber direction is It was wound so as to be in the same direction as the mandrel axis.

(D) Further, a wrapping tape (heat-resistant film tape) was wrapped around the wound product to cover the wound product, and was molded in a curing furnace at 130 ° C. for 90 minutes unless otherwise specified. The width of the wrapping tape was 15 mm, the tension was 34 N, the winding pitch (deviation amount at the time of winding) was 2.0 mm, and this was 2 ply wrapping.

(E) Thereafter, the mandrel was extracted, and the wrapping tape was removed to obtain a fiber-reinforced composite material tubular body.
In addition, except that the unidirectional prepreg using T700SC prepared in (6) above was used as the unidirectional prepreg, a tubular body made of fiber reinforced composite material using T700SC was prepared in the same manner as the above operations (a) to (e). did.

(9) Charpy impact test of fiber reinforced composite material tubular body The fiber reinforced composite material tubular body obtained in (8) above was cut to a length of 60 mm to produce a test piece having an inner diameter of 6.3 mm and a length of 60 mm. . A Charpy impact test was performed by applying an impact from the side of the tubular body at a weight of 300 kg · cm. From the swing angle, the following formula:
E = WR [(cosβ−cosα) − (cosα′−cosα) (α + β) / (α + α ′)]
E: Absorbed energy (J)
WR: Moment around the rotation axis of the hammer (N · m)
α: Hammer lift angle (°)
α ': Swing angle when the hammer is swung from the lift angle α (°)
β: Hammer swing angle after test specimen breakage (°)
The absorbed energy of impact was calculated according to Note that notches (notches) are not introduced into the test piece. The number of measurements was n = 5, and the average value was the Charpy impact value.

(10) Method for Measuring 0 ° Bending Strength of Unidirectional Laminate The 0 ° bending strength of the unidirectional laminated plate was measured as an index of bending strength of the fiber reinforced composite material. A test piece was cut out of the unidirectional laminate so as to have a thickness of 2 mm, a width of 15 mm, and a length of 100 mm. Using an Instron universal testing machine (Instron), the test piece was measured at a crosshead speed of 5.0 mm / min, a span of 80 mm, an indenter diameter of 10 mm, and a fulcrum diameter of 4 mm, and the bending strength was calculated. Moreover, after calculating | requiring real Vf based on the fabric weight of the produced prepreg, the obtained bending strength was converted into Vf60%.

(11) Softening point measurement (ring and ball method)
Measured by ring and ball method JIS-K7234 (2008).

(12) Measurement of glass transition temperature of epoxy component of cured resin product A cured resin product produced by the same method as in (3) above was cut out to a width of 13 mm and a length of 35 mm with a diamond cutter to obtain a test piece. Using a dynamic viscoelasticity measuring device (DMAQ800: manufactured by TA Instruments Inc.), the test piece was heated from 40 ° C. to 250 ° C. at a heating rate of 5 ° C./min, and the glass was bent in a frequency mode of 1.0 Hz. The transition temperature was measured. The onset temperature of the storage elastic modulus at this time was defined as the glass transition temperature. Tables 2 to 5 show the results. However, in the measurement of the glass transition temperature of the cured resin having a phase separation structure, two glass transition temperatures of the cured resin may occur, and the glass transition temperatures shown in Tables 2 to 5 are the lower glass transition temperatures. It is.

Example 1
40 parts of jER1007 as epoxy resin [A1] or [A2], 20 parts of jER630 as epoxy resin [B1] or [B2], 40 parts of Epicron 830 as epoxy resin [C1] or [C2], curing agent [D ] An epoxy resin composition was prepared using DICY7 as an amount of 0.9 equivalent of active hydrogen groups with respect to the epoxy groups of all epoxy resin components and 2 parts of DCMU99 as a curing accelerator. The resulting resin composition had a good viscosity at 80 ° C. The resulting epoxy resin composition was heated at 2.5 ° C./min and cured at 130 ° C. for 90 minutes. The obtained cured resin formed a fine phase separation structure and had good mechanical properties. Using the obtained epoxy resin composition and T800SC-24K as carbon fiber, a prepreg was prepared as described above. Using the obtained prepreg, the impact resistance of the fiber-reinforced composite material tubular body produced as described above and the 0 ° bending strength of the unidirectional laminate were good. The results are shown in Table 2.

(Examples 2 to 26, Comparative Examples 1 to 11)
Epoxy resin compositions were prepared in the same manner as in Example 1 except that the compositions shown in Tables 2 to 5 were changed. The evaluation results are shown in Tables 2-5. The cured resin obtained from the epoxy resin composition of each example formed a fine phase separation structure and had good mechanical properties. Moreover, the impact resistance property and the 0 ° bending strength of the unidirectional laminate were good for the tubular body made of fiber-reinforced composite material produced using the prepreg composed of the epoxy resin composition and carbon fiber obtained.

Since the epoxy resin composition of Comparative Example 1 did not use the epoxy resin [A1] or [A2], the obtained cured resin was uniform without phase separation, and the resin toughness value was insufficient. As a result, the impact resistance of the fiber-reinforced composite material tubular body produced using the resulting epoxy resin and carbon fiber was insufficient.

Since the epoxy resin composition of Comparative Example 2 did not use epoxy resin [B1] or [B2], the obtained cured resin was uniform without phase separation, and the resin toughness value was insufficient. As a result, the impact resistance of the fiber reinforced composite tubular body was insufficient.

Since the epoxy resin composition of Comparative Example 3 did not use the epoxy resin [B1] or [B2], the obtained cured resin was uniform without phase separation, and the elastic modulus was insufficient. As a result, the 0-degree bending strength of the unidirectional laminate produced using the obtained epoxy resin and carbon fiber was insufficient.

Since the epoxy resin composition of Comparative Example 4 did not use epoxy resin [A1] or [A2], the obtained cured resin was uniform without phase separation, and the resin toughness value was insufficient. As a result, the impact resistance of the fiber-reinforced composite material tubular body produced using the resulting epoxy resin and carbon fiber was insufficient.

Since the epoxy resin composition of Comparative Example 5 did not use epoxy resin [C1] or [C2], the obtained cured resin formed a coarse phase separation structure and lacked the elastic modulus. Furthermore, since the viscosity at 80 ° C. of the epoxy resin composition exceeded 200 Pa · s, voids occurred in the fiber-reinforced composite material. As a result, the mechanical properties of the fiber reinforced composite material produced using the obtained epoxy resin and carbon fiber were insufficient.

In the epoxy resin composition of Comparative Example 6, the obtained cured resin formed a fine phase separation structure, but the epoxy resin [C1] or [C2] was not used. Was lacking. As a result, the 0-degree bending strength of the unidirectional laminate produced using the obtained epoxy resin and carbon fiber was insufficient.

Since the epoxy resin composition of Comparative Example 7 does not use the epoxy resin [B1] or [B2], the obtained cured resin formed a uniform phase separation structure and lacked the elastic modulus. Furthermore, since the viscosity at 80 ° C. of the epoxy resin composition exceeded 200 Pa · s, voids occurred in the fiber-reinforced composite material. As a result, the 0 ° bending strength of the unidirectional laminate produced using the obtained epoxy resin composition and carbon fiber was insufficient.

Since the epoxy resin composition of Comparative Example 8 does not use the epoxy resin [A1] or [A2], the obtained cured resin formed a uniform phase separation structure and the resin toughness value was remarkably insufficient. As a result, the impact resistance of the fiber-reinforced composite material tubular body produced using the resulting epoxy resin and carbon fiber was insufficient.

Since the epoxy resin composition of Comparative Example 9 did not use the epoxy resin [C1] or [C2], the obtained cured resin formed a coarse phase separation structure and the resin toughness value was remarkably insufficient. As a result, the impact resistance of the fiber-reinforced composite material tubular body produced using the resulting epoxy resin and carbon fiber was insufficient.
Since the epoxy resin composition of Comparative Example 10 did not use the epoxy resin [A1] or [A2], the obtained cured resin formed a uniform structure, and the resin toughness value was extremely insufficient. As a result, the impact resistance of the fiber-reinforced composite material tubular body produced using the resulting epoxy resin and carbon fiber was insufficient.

Since the epoxy resin composition of Comparative Example 11 did not use the epoxy resin [A1] or [A2], the obtained cured resin formed a uniform structure and lacked the elastic modulus and resin toughness value. As a result, the 0 ° bending strength of the unidirectional laminate produced using the epoxy resin and carbon fiber obtained and the impact resistance of the fiber reinforced composite material tubular body were insufficient.

The epoxy resin composition of the present invention has a high elastic modulus and high toughness, and further has a low viscosity, so that it enables prepreg molding with a high fiber content. For this reason, the fiber reinforced composite material which has the outstanding impact resistance and intensity | strength can be obtained by combining an epoxy resin composition and a reinforced fiber. For this reason, the fiber-reinforced composite material obtained is preferably used for sports applications, general industrial applications, and aircraft applications.

Claims

An epoxy resin composition comprising an epoxy resin [A1], an epoxy resin [B1], an epoxy resin [C1] and a curing agent [D], wherein [A1] is a bisphenol type epoxy resin having a softening point of 90 ° C. or higher, [ B1] is a tri- or higher functional amine type epoxy resin, and [C1] a bisphenol F type epoxy resin having a number average molecular weight of 450 or less, and the epoxy resins [A1] to [C1] are contained in 100 parts by mass of all epoxy resin components. On the other hand, an epoxy resin composition satisfying a compounding ratio of [A1] 20 to 50 parts by mass, [B1] 30 to 50 parts by mass and [C1] 10 to 40 parts by mass.
The cured resin obtained by curing the epoxy resin composition has a phase separation structure having [A1] rich phase and [B1] rich phase, and the phase separation structure period is 1 nm to 5 μm. The epoxy resin composition according to claim 1.
An epoxy resin composition containing an epoxy resin [A2], an epoxy resin [B2], an epoxy resin [C2] and a curing agent [D] and satisfying the following conditions (1) to (4):
(1) The SP value of the cured resin [B2 ′] obtained by reacting the epoxy resin [B2] with the curing agent [D] and curing the epoxy resin [A2] and [C2] is the curing agent [D]. Greater than the SP value of any of the cured resin products [A2 ′] and [C2 ′] obtained by reacting with and curing the resin;
(2) The softening point of the epoxy resin [A2] is 90 ° C. or higher, and the softening points of the epoxy resins [B2] and [C2] are both 50 ° C. or lower;
(3) Epoxy resin [C2], dicyandiamide having an active hydrogen group of 0.9 equivalent to the epoxy group of epoxy resin [C2], and 2 parts by mass of 3- (3) to 100 parts by mass of epoxy resin [C2] Cured resin obtained by heating an epoxy resin composition comprising 3,4-dichlorophenyl) -1,1-dimethylurea from room temperature to 130 ° C. at a rate of 2.5 ° C./min and reacting at 130 ° C. for 90 minutes. And (4) a cured resin obtained by curing the epoxy resin composition has a phase separation structure including [A2] rich phase and [B2] rich phase. The period of the phase separation structure is 1 nm to 1 μm.
[A2] is a bisphenol type epoxy resin having a softening point of 90 ° C. or higher, [B2] is a trifunctional or higher amine type epoxy resin, and [C2] a bisphenol F type epoxy resin having a number average molecular weight of 450 or lower, and an epoxy Resins [A2] to [C2] have a mixing ratio of [A2] 20 to 50 parts by mass, [B2] 30 to 50 parts by mass and [C2] 10 to 40 parts by mass with respect to 100 parts by mass of all epoxy resin components. The epoxy resin composition according to claim 3, which is satisfied.
The epoxy resin composition according to any one of claims 1 to 4, wherein the epoxy resin [B1] or [B2] is a trifunctional aminophenol type epoxy resin.
The epoxy resin composition according to claim 1, wherein the curing agent [D] is dicyandiamide or a derivative thereof.
Further, at least one block copolymer [E] selected from the group consisting of SBM, BM, and MBM is added in an amount of 1 to 10 masses per 100 mass parts of the total epoxy resin component. The epoxy resin composition according to claim 1 comprising 6 parts;
Here, each of the blocks represented by S, B and M is linked directly or via some chemical structure via a covalent bond, and the block M is a polymethyl methacrylate homopolymer or methacrylic acid. A block comprising a copolymer containing 50% by mass or more of methyl, block B is a block incompatible with block M and has a glass transition temperature of 20 ° C. or less, and block S is non-blocking to blocks B and M The block is compatible and has a glass transition temperature higher than that of the block B.
The block copolymer [E] is a block copolymer represented by MBM, and the M block contains a monomer having a higher SP value than methyl methacrylate as a copolymer component. The epoxy resin composition described in 1.
The epoxy resin composition according to claim 7, wherein block B of the block copolymer in the block copolymer [E] is poly1,4-butadiene or poly (butyl acrylate).
2. The epoxy resin composition has a viscosity at 80 ° C. of 0.5 to 200 Pa · s, and a cured resin obtained by curing has a resin toughness value of 1.3 MPa · m 0.5 or more. 10. The epoxy resin composition according to any one of 1 to 9.
A prepreg comprising the epoxy resin composition according to any one of claims 1 to 10 and a reinforcing fiber.
A fiber-reinforced composite material obtained by curing the prepreg according to claim 11.
A fiber-reinforced composite material comprising a cured product of the epoxy resin composition according to any one of claims 1 to 10 and reinforcing fibers.